An example of the aforementioned semiconductor light-emitting device is a white light-emitting diode (hereinafter referred to as a white LED) including a solid-state semiconductor element and a wavelength converter that converts primary light emitted by the solid-state semiconductor element into light having a longer wavelength. In such a white LED, for example, a light-emitting diode (hereinafter referred to as a LED chip) with an InGaN-based compound semiconductor used as a light-emitting layer has been used widely as a solid-state light-emitting element. Further, as the wavelength converter, for example, a resin phosphor film having a structure in which powdered phosphor is dispersed in a translucent resin has been adopted.
Recently, there is a growing demand for higher output semiconductor light-emitting devices. However, when the light output of phosphor excitation light emitted by the LED chip is increased by the higher output semiconductor light-emitting device, heat is generated due to energy loss (Stokes loss) accompanying phosphor wavelength conversion. This heat then is accumulated in the resin phosphor film and causes a temperature rise in the resin phosphor film, which results in temperature quenching of the phosphor and a decrease in photon conversion efficiency.
Further, the temperature rise in the resin phosphor film, etc., and strong irradiation of primary light emitted by the LED chip lead the translucent resin of the resin phosphor film to, for example, chemically react with peripheral members and the atmosphere. This adversely affects various properties of the translucent resin, such as decreases in light output, translucency, or the like.
Therefore, in order to suppress the temperature rise in the wavelength converter, it has been proposed to adopt, as the wavelength converter, a ceramic-based formed body having high thermal conductivity and superior heat dissipation properties, such as translucent phosphor ceramic, phosphor glass, and composite ceramic with an optical function (see, for example, Patent Literatures 1 and 2).